Using a sulfur-bearing silane to improve rubber formulations for potential use in industrial rubber articles

This is an Accepted Manuscript of an article published by Taylor & Francis in Journal of Adhesion Science and Technology on 13/08/2012, available online: http://dx.doi.org/10.1080/01694243.The availability of the coupling agent bis (3-triethoxysilylpropyl)-tetrasulfide (TESPT) has provided an opportunity for enhancing the reinforcing capabilities of precipitated amorphous white silica in rubber. Styrene-butadiene rubber, synthetic polyisoprene rubber (IR), acrylonitrile-butadiene rubber, and natural rubber (NR) containing the same loading of a precipitated silica filler were prepared. The silica surface was pretreated with TESPT, which is a sulfur-bearing bifunctional organosilane to chemically bond silica to the rubber. The rubber compounds were subsequently cured by reacting the tetrasulfane groups of TESPT with double bonds in the rubber chains and the cure was optimized by adding sulfenamide accelerator and zinc oxide. The IR and NR needed more accelerators for curing. Surprisingly, there was no obvious correlation between the internal double bond content and the accelerator requirement for the optimum cure of the rubbers. Using the TESPT pretreated silanized silica was a very efficient method for cross-linking and reinforcing the rubbers. It reduced the use of the chemical curatives significantly while maintaining excellent mechanical properties of the cured rubbers. Moreover, it improved health and safety at work-place, reduced cost, and minimized damage to the environment because less chemical curatives were used. Therefore, TESPT was classified as "green silane" for use in rubber formulations

Investigating ice-ocean interactions in Kangerdlugssuaq Fjord over the past ∼600 years through proxy reconstructions

International audienceThere is a growing body of evidence demonstrating that changes in warm water inflow to Greenlandic fjords are linked to the rapid retreat of marine-terminating outlet glaciers. This process is thought to be responsible for a substantial component of the increased mass loss from the Greenland Ice Sheet over the last two decades. Sediment cores from glaciated fjords provide high-resolution sedimentological and biological proxy recordswhich can be used to evaluate the interplay of warm water inflow and glacier calving over timescales longer than the instrumental record.In this study, a short core (1.5m) positioned at the head of Kangerdlugssuaq fjord is investigated to establish a multi-proxy record of glacier behaviour and oceanographic conditions. The core covers the past ∼600 years, spanning back to the start of the Little Ice Age. Grain-size analysis is performed to quantify ice-rafted debris (IRD), a parameter related to the calving intensity of Kangerdlugssuaq glacier. Bottom current strength isreconstructed by measurements of the mean sortable silt; periods of vigorous current flow are assumed to be due to enhanced warm water inflow. A record of sea surface temperatures is derived from alkenone paleothermometry (Uk’ 37), and the origin of the alkenones is discussed (in situ vs. advection). Reconstructions of ice-oceaninteractions on a longer timescale provide a baseline to better understand the recent -and potentially future- retreat of marine-terminating glaciers in Greenland

Evaluating ice-rafted debris as a proxy for glacier calving in Upernavik Isfjord, NW Greenland

International audienceRecords of ice‐rafted debris (IRD) in sediments are commonly used as a proxy for iceberg production and to reconstruct past changes of glacier stability. However, the interpretation of IRD is complex as multiple processes modulate its variability. This study investigates the relationship between IRD variability and glaciological change by measuring IRD records from Upernavik Fjord and comparing these to frontal positions of Upernavik Isstrøm during the past century. Results show that the spatial variability of IRD deposition throughout the fjord is high, indicating that randomness inherent to IRD distorts the calving signal. However, we investigate whether IRD records can be combined to improve the reconstruction, as previously suggested, and show the importance of core site selection and number of cores on this approach. The outer‐fjord core compares relatively well to the observed front positions and this is reflected in the composite record: increased IRD deposition in 1937–1946, 1968–1980, and 1996–1999 occurred during periods of faster retreat. Comparison with climatic records shows that the calving episodes in the late ‘30 s/early ‘40 s and late ‘90 s are related to warm ocean and air temperatures, whereas intensified retreat and calving during the ‘70 s reflects partly an internal glacier response to the fjord geometry

Investigating the interaction between ocean current variability and glacier activity by Thrym glacier, SE-Greenland

International audienceHeat transport via ocean currents can have a crucial impact on the melting of marine terminating glaciers in Greenland. To investigate the influence of ocean temperature changes on the glaciodynamics of Thrym glacier over longer timescales we present a marine sediment record from the Skjoldungen fjord by Thrym Glacier in SE Greenland. 210Pb-dating combined with a radiocarbon date reveals that the core covers the past 220 years from 1790 AD until 2011 AD. High-resolution grainsize analyses representing the calving activity of Thrym glacier and sea surface temperature (SST) derived from alkenones were conducted. During the investigated timespan, the alkenone based SSTs vary between 5 and 12 ◦C. The high temperatures, in comparison with present SST in thefjord of 0-2 degree Celsius, indicate, in similarity with other alkenone reconstructions from SE Greenland, that the alkenones were produced further off shore in the Irminger Sea and advected with the inflow of surface waters into the fjord. We compare this record of Irminger SST variability with the reconstructed calving activity and furthermore with other similar studies in SE- Greenland. This will help to understand the regional sensitivity ofGreenland Ice Sheet (GIS) melt resulting from heat transport associated with the subpolar gyre circulation and aid in our understanding of the future behavior of the GIS under a warming climat

Sea surface temperature variability on the SE-Greenland shelf (1796-2013 CE) and its influence on Thrym Glacier in the fjord Nørre Skjoldungesund

This data set includes grain size analyses and SST reconstructions from core AXC1432 in Nørre Skjoldungensund, SE-Greenland. Furthermore it contains water temperatures calculated from mesurements from https://www.ICES.dk and from the HadISST dataset. Heat transport via ocean currents can affect the melting of marine-terminating glaciers in Greenland. Studying past changes of marine-terminating glaciers allows assessing the regional sensitivity of the Greenland Ice Sheet (GrIS) to ocean temperature changes in the context of a warming ocean. Here, we present a high-resolution multi-proxy marine sediment core study from Skjoldungen Fjord, close to the marine-terminating Thrym Glacier. Grain-size data is obtained to reconstruct the calving activity of Thrym Glacier, sortable silt is used as a proxy for fjord water circulation and sea surface temperatures (SSTs) are reconstructed from alkenone paleothermometry (Uk'37). Measurements of 210Pb, 137Cs and 14C indicate that the core covers the past 220 years (1796 CE to 2013 CE). Comparisons with modelled SST data (HadISST) and instrumental temperatures (ICES) suggest that the SST proxy record reflects temperature variability of the surface waters over the shelf and that alkenones are advected into the fjord. Additionally, average temperatures and the amplitude of fluctuations are influenced by alkenones advected from upstream the Irminger Current. We find that the SST record compares well with other alkenone-based reconstructions from SE-Greenland, and thus features regional shelf water variability. The calving activity as well as the terminus position of Thrym Glacier did not seem to respond to the SST variability. Limited ice-ocean interactions owing to the specific setting of the glacier would explain this. Instead, the fjord circulation may have been influenced by enhanced meltwater production as well as to larger scale changes in the AMOC

A 2000-year record of ocean influence on Jakobshavn Isbræ calving activity, based on marine sediment cores

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